How to Hide Subscribe2 Admin Menus

function plt_hide_subscribe2_menus() {
	//Hide "Subscribe2".
	remove_menu_page('s2');
	//Hide "Subscribe2 → Your Subscriptions".
	remove_submenu_page('s2', 's2');
	//Hide "Subscribe2 → Subscribers".
	remove_submenu_page('s2', 's2_tools');
	//Hide "Subscribe2 → Settings".
	remove_submenu_page('s2', 's2_settings');
	//Hide "Subscribe2 → Send Email".
	remove_submenu_page('s2', 's2_posts');
}

add_action('admin_menu', 'plt_hide_subscribe2_menus', 11);

Where do I put this code?